I'm not sure of the answer to your interesting question, but I did have a thought about the possibility that at least one of those "secret societies" may in fact have fabricated legends about other ones to distract us from who is really up to what.

Think about control of information by someone in such a high and influential position and the probability of "red herrings" to throw us off the scent.

I think if I was a shady, underhanded greed-monger in a secret society bent on world domination I might invent stories about other societies for people to focus on.